An odd confluence of important issues came together in a federal courtroom in Alexandria on Tuesday: the criminal investigation of WikiLeaks, free speech and social networking.

It all stemmed from the government's attempts to get personal information from the Twitter accounts of three people linked to the WikiLeaks probe. Their lawyers argued that the data - screen names, mailing addresses, telephone numbers, credit card and bank account information, and Internet protocol addresses - are protected by the First Amendment. Prosecutors said the request is a routine part of their criminal probe.

It was the opening salvo in what experts expect to be a long and difficult investigation of WikiLeaks founder Julian Assange and others suspected of disclosing thousands of classified documents on the anti-secrecy Web site.

Tuesday's arguments went to the heart of a larger debate about WikiLeaks - whether the posting of the documents was free speech or a violation of national security. They also provided a high-profile test of outdated rules about what data the government can seize in the new world of social networking.

In the courtroom, John Keker, a lawyer representing one of the Twitter clients, said the users' data would give the government a map of people tied to WikiLeaks and essentially halt free speech online. He noted how social networking sites have been used in Egypt and Tunisia, where citizens have pushed for government changes, and suggested that such a broad request by the U.S. government in this case would put a stop to that.

John Palfrey, a Harvard law professor not associated with the case, said the government is using 18th-century arguments with 21st-century technology.

"These are not new arguments, but they're being used in a really interesting and important way that has a twist to them in light of social media," he said.

New details of probe

Until now, there has been little public evidence of the government's criminal investigation of WikiLeaks, a probe Attorney General Eric H. Holder Jr. announced in late November.

Information began to come out last week after U.S. Magistrate Judge Theresa Carroll Buchanan granted a motion from the three Twitter clients to unseal some filings in the case. Tuesday's hearing was the first public debate in the criminal investigation of Assange and others.

Court documents reveal that the government has asked for personal Twitter information from Assange; Bradley Manning, the Army private who is suspected of supplying classified material to the Web site; Birgitta Jonsdottir, a former WikiLeaks activist who is also a member of Iceland's Parliament; and two computer programmers, Rop Gonggrijp, a Dutch citizen, and Jacob Appelbaum, an American.

On Tuesday, defense lawyers tried to convince Buchanan that she should overturn her December ruling that ordered Twitter to disclose its clients' data, as well as unseal documents in the case, including requests from prosecutors to get information from other technology companies.

Aden Fine, a lawyer with the American Civil Liberties Union who represents Jonsdottir, said that his client and the two others apparently have been "swept up into the government's investigation of WikiLeaks" and that the government's requests shouldn't be granted, nor should it be done using sealed documents.

But prosecutors from the U.S. Attorney's Office of the Eastern District of Virginia disagreed, saying in court that their request to Twitter was routine and that releasing documents in the case would damage their investigation of WikiLeaks. It's unclear whether Twitter even collects all the information requested by the government.

'It is not about politics'

After the hour-long hearing, Buchanan said she would take the case "under consideration." She is expected to issue a written order and opinion.

Keker argued that turning over the Twitter customers' information would also violate the Fourth Amendment, which protects against warrantless searches.

But Buchanan questioned whether Keker was exaggerating the amount of information that her Dec. 14 order allowed the government to get.

"What they're seeking is location data and timing data," Buchanan said. The government is not seeking data that would reveal the content of Twitter messages.

John Davis, an assistant U.S. attorney in Alexandria, said the government's request was routine.

"This is a standard - as this court knows well - investigative measure used in criminal investigations every day of the year all over the country," Davis said. "This is not about association rights. It is not about politics. It is about facts and evidence."

In court papers, defense lawyers accuse the government of "snooping because of what the [individuals] have said and because of who they know."

Manning has been accused by the military of leaking a video that showed two U.S. helicopters in Iraq firing at people on the ground in 2007. Jonsdottir was one of the producers of an edited version of the video.

The defense lawyers' argument that the government's request violates the First Amendment is, legal experts say, a new twist in fighting data-seizure in the world of social networking sites.

The number of court orders and subpoenas from authorities demanding that technology companies and telecommunications firms turn over information about their clients is rapidly growing. But the rules protecting personal information are spotty and not up to date with Internet technology. Experts say they were meant to deal with telephone records, not such evolving technology as e-mails and tweets.

Chris Calabrese, a lobbyist for the ACLU in Washington, said the laws pertaining to accessing communications date back to 1986.

"It is pre-www. We're using tools for accessing information on e-mail, social networking sites that were never contemplated," he said.

A spokesman for Twitter recently said the company had no comment on WikiLeaks, but he pointed to a Jan. 28 blog post. It said that the company's "position on freedom of expression carries with it a mandate to protect our users' right to speak freely and preserve their ability to contest having their private information revealed."